ABSTRACT
E-mail: mplath@bio.uni-frankfurt.de 2Texas A&M University, Department of Fish and Wildlife Sciences, 2258
TAMU, College Station, TX 77843-2258 USA 3University of Zürich, Institute of Zoology, Winterthurerstrasse 190
CH-8057 Zürich, Switzerland
The Atlantic molly (P. mexicana) is a widespread freshwater fi sh living along the Atlantic coast of Mexico and Central America (Miller 2005). It inhabits coastal lagoons, estuaries, lowland ponds and rivers up to highland streams (Bussing 1998, Miller 2005). Mollies are small fi sh less than 10 centimeters long, and belong to the family Poeciliidae (livebearers). Poeciliids give birth to fully developed young, which are instantly independent. Males use a modifi ed anal fi n, the so-called gonopodium, to transfer sperm bundles (spermatozeugmata) to the female during copulation (Rosen and Bailey 1963, Meffe and Snelson 1989). In the southern Mexican Cueva del Azufre system, P. mexicana has colonized at least two caves. Cavernicolous P. mexicana have been referred to as the cave molly (Gordon and Rosen 1962, Parzefall 2001). Cave mollies are the only known poeciliids that naturally inhabit subterranean habitats (Proudlove 2006). The only other known poeciliid species occurring in a cave is Gambusia affi nis introduced into the ‘Spunnulate’ dolinas system of Torre Castiglione in southeastern Italy (Camassa 2001). Various aspects of
the evolutionary ecology of P. mexicana from the Cueva del Azufre system have been studied thoroughly during the past decades. Today, the cave molly ranks among the best-studied cavefi shes worldwide along with the cave form(s) of the Mexican tetra Astyanax mexicanus (see chapters 5 and 6 in this volume). This chapter provides a synopsis particularly over some recent advances in the understanding of the evolutionary ecology of cavernicolous P. mexicana.
